WorldWide Drilling Resource

26 SEPTEMBER 2013 WorldWide Drilling Resource ® Outsmarting the Dirt ~ Groundwater Sampling Part 2 by Thomas D. Dalzell, CWD Director of Environmental Research AMS, Inc. Groundwater Sampling Prior to installation of groundwater monitoring wells, groundwater samples can be collected through a variety of direct push (DP) tooling. There are sev- eral types of retractable groundwater samplers available for sampling ground- water where there are contaminants dissolved in the upper/highest level of the groundwater table. There are also groundwater samplers for determining the conditions of the groundwater when a contaminant is possibly sinking with- in the groundwater (vertical delineation of contaminants in the groundwater). If it is not possible or practical to sample through DP tooling, temporary groundwater monitoring wells can be installed. If it is known or anticipated that groundwater has been impacted by contaminants, or if the groundwater has the potential to be impacted in the future by contaminants in the soil, it is important to implement a groundwater monitoring program. If a long-term groundwater moni- toring program is needed at the site, small-diameter prepacked screen ground- water monitoring wells (direct push wells) can be installed. In addition, conventional groundwater monitoring wells can also be installed if the project and applicable regulations warrant this type of activity. Direct Push Wells Direct push wells are approved and accepted by federal, and many state regulatory agencies. ASTM International has several methods and/or procedures directly related to the use and installa- tion of direct push wells. The sizes of direct push wells range from ½-inch nominal inside diameter (ID) to 2-inch ID. The practical achievable depth is based on lithology and the desired well ID size, but in general, less than 80 feet below ground surface (bgs) is the aver- age depth; although it is possible to install direct push wells to depths of over 100 feet bgs. Direct push wells can be secured exactly like conventional wells, and de- velopment of the prepacked section can be a simple surging. They can be used to calculate gradient magnitude and direction, and there is a variety of small- diameter instrumentation which can accurately take depth measurements, measure useful parameters, and collect samples. For certain lithologies and depths, it is sometimes necessary to sample soil to achieve the target depth when installing direct push wells. It is very important all sampling and installation techniques are conducted in a way that does not negatively affect/impact the soil and groundwater. Once the condition of the ground- water has been determined, the data can be used as part of the development of a remedial action plan. Groundwater Sampling will conclude next month. Tom Thomas D. Dalzell may be contacted via e-mail at admin@ worldwidedrillingresource.com &% ! "" * "(%$ ))) (" $( ' & $ %# # " (" $( $ ( " !" !! ! &% ! % ! (" $( & $ $ $ " ! $ $ ! ! $ ! $ # $ $ $